When an internal auditor suspects fraudulent activity, such as erroneous payments to a fraudulent bank account, the appropriate course of action is to escalate the concern to the engagement supervisor (Option D).
This step ensures that the issue is handled with the necessary urgency and oversight. According to the IIA Standards, particularly Standard 2060: Reporting to Senior Management and the Board, the CAE must communicate significant risk exposures and control issues, including fraud risks, to senior management and the board. Escalating the concern ensures the appropriate levels of the organization are aware and can take timely action.
IIA Standards, Standard 2060: Reporting to Senior Management and the Board IIA Practice Guide: Internal Auditing and Fraud

Demonstrating due professional care involves thorough testing and evaluation of evidence. The internal auditor exhibited due professional care by selecting a sample of purchase orders above a specific threshold and obtaining documentation for each to verify compliance with the required bidding process. This methodical approach ensures that audit findings are based on sufficient, appropriate evidence and that conclusions about the effectiveness of controls are well-supported.
International Standards for the Professional Practice of Internal Auditing, particularly those related to due professional care and evidence evaluation.

When an internal auditor suspects that a tender was tailored for a specific bidder, the next appropriate action is to analyze the technical terms and conditions of the tender (Option D). This step involves a detailed examination of the tender documentation to identify any specific terms that may have been included to favor a particular bidder. Such an analysis can provide evidence of bias or manipulation. According to the IIA Standards, auditors must gather sufficient, reliable, and relevant evidence to support their findings (Standard
2310: Identifying Information).
IIA Standards, Standard 2310: Identifying Information
IIA Practice Guide: Evaluating Third-party Risk Management

The chief audit executive (CAE) would be required to decline a consulting engagement if there is no available expertise on the internal audit team to perform it. According to IIA standards, internal auditors must possess the knowledge, skills, and other competencies needed to perform their responsibilities. Accepting an assignment without the requisite expertise could impair the effectiveness and credibility of the audit function.
IIA Standards for the Professional Practice of Internal Auditing

According to IIA guidance, an appropriate role for the internal audit activity includes coaching management in responding to risks. This involves advising, counseling, and providing insights based on analyses and assessments in a way that adds value and improves an organization's operations without assuming management's responsibilities. Implementing risk responses, imposing risk management processes, or setting the risk appetite would compromise the independence of the internal audit function.
Institute of Internal Auditors (IIA) - International Professional Practices Framework (IPPF)